1. Field of the Invention
The present invention relates to sound reproduction and more particularly to systems and methods to provide a more powerful, broader bandwidth loudspeaker horn.
2. Description of the Related Art
When large acoustic powers are required for music or voice sound reinforcement, large arrays of loudspeakers are typically used. However, it has been observed that there are certain self destructive relationships generating audible interference in such systems and that the audience may be better served by a more powerful single (or two for stereo, etc.) source(s) of sound. Unfortunately there are audio output limitations on a practical single source loudspeaker. The back bone of all sound systems are horn loudspeakers which typically handle all the frequencies above the Bass or mid-range of the sound. Horns of current art have a number of problems, which cause them to be largely ignored in the high fidelity area.
In professional sound systems, one finds that there are also limits due to the physics involved and materials available to construct the loudspeaker drivers as to how powerful a single horn can be made. Additionally, audio distortions peculiar to horn drivers are related to the loudness and bandwidth of sound being produced. This problem is called xe2x80x9cthroat distortionxe2x80x9d and is more or less a product of the intensity of the sound times the distance it travels in the horn.
Classical horn theory says that a horn is an impedance transformer with the driver at one end and the acoustic load at the other. The advantage of the horn is that it can greatly increase the efficiency and acoustic power over the driver alone. Looking further, one finds that a horn has a low frequency cutoff defined by the flare rate of the horn, for example the classic exponential horn may double its area, e.g., every 24 inches for a 30 Hz flare and every 2.4 inches for a 300 Hz flare and so on. The louder the audio output, and the wider the response (longer horn due to accommodate operation at lower frequencies), the worse the distortion. Starting at the driver diaphragm of a conventional loudspeaker, the sound pressure is highest at the throat of the horn and as the flare of the horn increases in area, the sound pressure falls roughly inversely proportional to the area increase. In this case one finds a horn with a higher low cutoff (faster flare) has less distortion for the same intensity. This throat distortion problem is not dependant on the materials the driver is constructed from and is probably the primary limiting factor in the loudness/bandwidth.
Accordingly, it would be desirable to provide a sound reproduction system employing single source loudspeakers taking advantage of the frequency response of the loudspeaker horn itself, while avoiding signal distortions to present an unified audio signal with a sum of the operating frequency ranges from the sound reproduction system.
The present invention provides at least a single horn which has multiple drivers arranged to utilize the sections of the horn positioned for desired frequency characteristics of the horn, rather than using several nested horns. Whereas in this approach, there is only one horn and all of the drivers are highly coupled to it. In a described embodiment, the angle of the wall is the same for each case to provide several loudspeaker sources along the horn with the drivers being positioned out of the way of the audio path.
Whereas, normally horns may be provided, one each for each audio range, with woofer cones on the face of the final flare as a convenient placement out of the way, such systems are not actually horn loaded with a series of drivers combined to provide a three-way horn. A multi-way speaker system is provided herein to include a three-way system with a mid-range, a tweeter, and a base speaker for a transformation over the entire range where all of the drivers are acoustically highly coupled to each other. Thus the horn is designed to do more than one job, partitioning the conical flare to put the full frequency range through the single loudspeaker system.
Briefly summarized, the present invention relates to systems and methods for sound reproduction employing a unity summation aperture loudspeaker horn taking advantage of the frequency response of horn flare characteristics for positioning of audio drivers along the outer wall of the loudspeaker horn. The loudspeaker horn may be embodied as any of a variety of pyramid shapes which allows for sections for driver positioning in correlation with the frequency response of the horn. Positioning the driver sources along the sides of the horn and out of the way of the audio field facilitates at least two modes of operation including a transformation operation for acoustical impedance matching and a waveguide operation for directing the reproduced audio signals. The single horn, multi-driver approach provides highly coupled audio drivers to generate sound reproduction employing unity summation aperture loudspeakers.
The appended claims set forth the features of the present invention with particularity. The invention, together with the advantages described herein may be best understood by the following detailed description taken in conjunction with the accompanying drawings.